SOUTH SAN FRANCISCO, Calif., April 04, 2016 (GLOBE NEWSWIRE) -- Portola Pharmaceuticals (NASDAQ:PTLA), announced today that it has entered into a clinical collaboration agreement with Daiichi Sankyo to develop andexanet alfa as an antidote for edoxaban, Daiichi Sankyo’s Factor Xa inhibitor, in Japan.

Portola is developing andexanet alfa, a U.S. Food and Drug Administration (FDA)-designated Breakthrough Therapy, for patients treated with a direct or indirect Factor Xa inhibitor when reversal of anticoagulation is needed, such as for life-threatening or uncontrolled bleeding or emergency surgery and urgent procedures.

Under the terms of the agreement with Daiichi Sankyo, Portola will receive an upfront payment and is eligible to receive an additional milestone payment based on Japanese Ministry of Health, Labor and Welfare (MHLW) approval of andexanet alfa as an antidote for edoxaban. Daiichi Sankyo will provide technical support and fund all clinical studies of andexanet alfa with edoxaban in Japan. Daiichi Sankyo will receive no commercial or financial rights under this agreement.

This agreement follows recent agreements with Bristol-Myers Squibb (BMS), Pfizer Inc. and Bayer Healthcare to develop and commercialize andexanet alfa in Japan. Under those agreements, BMS and Pfizer will be responsible for development, regulatory and commercial activities for andexanet alfa in Japan. Bayer will fund development of andexanet alfa as an antidote for rivaroxaban in Japan. Under this new agreement with Daiichi Sankyo, edoxaban will also be included in the andexanet alfa clinical development program in Japan.

Portola previously entered into eight separate non-exclusive clinical collaboration agreements with Daiichi Sankyo, BMS, Pfizer, Bayer and Janssen to support Phase 2 and Phase 3 studies of andexanet alfa and edoxaban in the United States, Europe and Japan. Portola may receive additional payments under these agreements. Portola retains all rights, including full commercial and financial rights, for andexanet alfa outside of Japan.

About the Need for a Factor Xa Inhibitor Antidote

Commensurate with the increase in use of Factor Xa inhibitors, the number of hospital admissions due to bleeding associated with these agents continues to grow. Annually, 1 to 4 percent of patients treated with Factor Xa inhibitors may experience major bleeding, and an additional 1 percent may require emergency surgery.

In Japan, three oral Factor Xa inhibitors are currently on the market – Daiichi Sankyo’s edoxaban, BMS and Pfizer’s apixaban, and Bayer HealthCare’s rivaroxaban. Based on data from IMS Health, in the 12 months ending September 2015, sales of these novel oral anticoagulants in Japan exceeded $800 million. There is an unmet need for an antidote for some patients.

About Andexanet Alfa

Andexanet alfa, an investigational drug, is a modified human Factor Xa molecule that acts as a decoy to target and sequester with high specificity both oral and injectable Factor Xa inhibitors in the blood. Once bound, the Factor Xa inhibitors are unable to bind to and inhibit native Factor Xa, thus allowing for the restoration of normal hemostatic processes. Andexanet alfa is the only compound being studied as an antidote for Factor Xa inhibitors that directly and specifically corrects anti-Factor Xa activity – the anticoagulant mechanism of these agents.

Portola’s Biologics License Application (BLA) for andexanet alfa was accepted for filing by the FDA’s Center for Biologics Evaluation and Research (CBER) and assigned a Prescription Drug User Fee Act (PDUFA) date of August 17, 2016.

The BLA was based on data from preclinical, Phase 1 and 2, manufacturing and Phase 3 studies. The Phase 3 ANNEXA™ (Andexanet Alfa a Novel Antidote to the Anticoagulant Effects of FXa Inhibitors) studies evaluated the safety and efficacy of andexanet alfa in reversing the anticoagulant activity of the Factor Xa inhibitors rivaroxaban and apixaban in healthy volunteers. Results of those studies were published by The New England Journal of Medicine in November 2015. The BLA also included limited adjudicated efficacy and safety data from initial patients enrolled in the ongoing Phase 4 ANNEXA-4 study. Portola is currently evaluating andexanet alfa in this global, single-arm, open-label confirmatory study in patients receiving apixaban, rivaroxaban, edoxaban or enoxaparin (a low molecular weight heparin and indirect Factor Xa inhibitor) who present to the hospital with an acute major bleed.

About Portola Pharmaceuticals, Inc.

Portola Pharmaceuticals is a biopharmaceutical company developing product candidates that could significantly advance the fields of thrombosis and other hematologic diseases. The Company is advancing its three programs using novel biomarker and genetic approaches that may increase the likelihood of clinical, regulatory and commercial success of its potentially life-saving therapies. These programs include betrixaban, an oral, once-daily Factor Xa inhibitor; andexanet alfa, a recombinant protein designed to reverse the anticoagulant effect in patients treated with an oral or injectable Factor Xa inhibitor; and cerdulatinib, a Syk/JAK inhibitor in development to treat hematologic cancers. Portola's partnered program is focused on developing selective Syk inhibitors for inflammatory conditions. For more information, visit www.portola.com and follow the Company on Twitter @Portola_Pharma.

Forward-looking Statement

Statements contained in this press release regarding matters that are not historical facts are "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. Because such statements are subject to risks and uncertainties, actual results may differ materially from those expressed or implied by such forward-looking statements. Such statements include, but are not limited to statements regarding clinical and commercial development plans for andexanet alfa in Japan. Risks that contribute to the uncertain nature of the forward-looking statements include: failure to obtain FDA approval for one or more of our product candidates; our expectation that we will incur losses for the foreseeable future and will need additional funds to finance our operations; the results of our clinical trials related to the efficacy and safety of our product candidates; our potential inability to manufacture andexanet alfa on a commercial scale in a timely or cost-efficient manner; the accuracy of our estimates regarding expenses and capital requirements; the ability of us and our partners to successfully execute under our collaboration agreements; regulatory developments in the United States and foreign countries; our ability to obtain and maintain intellectual property protection for our product candidates; and our ability to retain key scientific or management personnel. These and other risks and uncertainties are described more fully in Portola's most recent filings with the Securities and Exchange Commission, including its Annual Report on Form 10-K, which was filed on February 29, 2016. All forward-looking statements contained in this press release speak only as of the date on which they were made. Portola undertakes no obligation to update such statements to reflect events that occur or circumstances that exist after the date on which they were made.